The field of this invention is related mostly to text entry into a computer system, particularly to handheld computers and personal digital assistants (PDAs), mobile phones and television sets and other electronic and computer based devices. More specifically it improves some of the existing methods to disambiguate user entry on a regular or miniaturized keyboard. The proposed solution also uses novel data inputs (such as directional information) to successfully retrieve the required word from the dictionary.
Text input is an important task for the computer user. The QWERTY keyboard is the most common text entry device on a desktop computer. Mobile electronic devices such as PDAs and mobile phones do not usually have space for full QWERTY keyboards and, with their widespread adoption, the need for improved text entry on devices with limited keypads and small screen size has emerged.
In the case of mobile phones, text entry is normally accomplished using numerical keys as surrogates for letters. In the typical arrangement each key corresponds to 3 or more letters or punctuation marks, selection of the correct letter requiring multiple depressions of the same key, which can be time consuming. This disadvantage is exacerbated when using less common words, the letters of which may require a greater number of depressions of the same key. This situation is improved somewhat by the common practice of using “predictive” text entry where the most likely letters in a given word are inferred by the software, reducing the letter choice options at any given point in entering a word. This method of text entry is becoming more cumbersome with the expanding applications of more sophisticated mobile phones to the extent that some smartphones incorporate full, albeit rather small, QWERTY keyboards. However operating miniature keyboards by hand is difficult as the spaces between keys and the keys themselves are often smaller than the operator's finger. This limits the minimum size one can practically make a physical QWERTY keyboard. The smaller the keyboard the more likely there will be data entry errors. A method is needed to cope better with the inevitable ambiguity and errors in entering data on small or limited keyboards, beyond predictive text entry.
An alternative to finger operation of reduced-size keyboards is the operation by stylus on virtual keyboards, which are now available in devices such as PDAs. Virtual keyboards can be displayed on a screen, whereby letters can be entered by tapping the appropriate key or symbol with the stylus. The keyboard provided on the screen is typically the familiar QWERTY layout. Nevertheless, stylus keyboarding requires intense concentration, is slow compared to using a full keyboard and, like physical miniature keyboards, is likely to result in many entry errors.
Other improvements in text entry on mobile devices have concentrated on individual letter input e.g. handwriting recognition software, which is common on PDAs and on Tablet PCs, but tends to be slower than keyboard entry for many people. There are also other stylus/keyboard letter selection mechanisms that have been developed such as the Unistrokes alphabet, where every letter is written with a single stroke, but the more frequent ones are assigned simpler strokes.
It is important to not to rely on accurate entry of all the letters in a word if speed of text entry is to be improved beyond using a stylus to tap each letter on a virtual keyboard.
An example of recent improvements to word entry on a virtual keyboard is provided by a system from IBM (US patent US2004/120583). This is a system that recognizes words by the shape that is made by a stylus as it passes through the letters on a virtual keyboard. This shape is matched to a list of stored word patterns. The system requires a certain level of training and significant computing calculations to match patterns and to cope with errors. Such systems often have a significant processing requirement and may be subject to slow response times. Moreover, systems of this kind sometimes have a relatively low tolerance for error beyond which the word simply cannot be recognized. Such systems are based on recognizing words from a pattern traced out on an input device, rather than the actual keys activated. However, such systems use patterns based on omnidirectional movements i.e. the patterns are complex because each element of movement can take place in an infinity of directions. The systems are capable of accurately identifying intended words, but maintain a high volume of information at all stages of data processing. This may be onerous on limited processing resources, especially in small devices such as mobile telephones and PDAs.
It is therefore an objective of the current invention to provide a text input system that overcomes all of the above technical shortcomings. In fact simpler patterns are adequate input for data entry and word recognition and the current invention is based on this concept, i.e. it is unnecessary to track omnidirectional patterns. It reduces the information derivable from tracking key movements, thus initially providing relatively low accuracy in word identification. The system may then compensate for inaccuracies by applying supplementary disambiguation techniques.
The text input system reduces the need to be accurate when entering text, improving the utility of small keypads and which leverages user knowledge of and familiarity with existing keyboard layouts such as the QWERTY keyboard.
A further advantage of the invention is that it will also allow the use of limited e.g. numeric keypads as efficient surrogates of full QWERTY keypad layouts allowing application in small electronic devices such as mobile phones and consumer electronic devices such as TV remote controls.